How can I test if a letter in a string is uppercase or lowercase using JavaScript?
views:
2197answers:
6
+5
A:
function isUpperCase(myString) {
return (myString == myString.toUpperCase());
}
function isLowerCase(myString) {
return (myString == myString.toLowerCase());
}
Josh
2009-06-22 13:32:02
i believe this solution only works if the string is one character long and that character is the character of interest...you'd need to get the character first before calling either of these methods
zaczap
2009-06-22 13:41:16
@zaczap - incorrect. These will transform (and then test) the entire string.
scunliffe
2009-06-22 13:42:32
+1 to the comments - this answer is slightly off, in respect to the original question, which asked about a letter in a string (Not the whole string)
belugabob
2009-06-22 13:47:34
Let's not forget strict equality checking! === FTW!
J-P
2009-06-22 13:49:56
@all - correct it will only test against a whole string - you could loop through the letters within a string to test each one.
Josh
2009-06-22 13:52:50
You could loop and check each - but that wasn't the question -- :)
Hugoware
2009-06-22 13:53:47
+8
A:
if (character == character.toLowerCase())
{
// The character is lowercase
}
else
{
// The character is uppercase
}
Daniel Vandersluis
2009-06-22 13:32:21
+2
A:
String.prototype.isUpper = function(pos){return this.charCodeAt(pos)<90;};
alert('stringIsUpperCaseTest'.isUpper(7)); //true
String.prototype.isUpper performs a very simple test. It's just the idea, you can figure out yourself how to exclude non alphabetic characters (65-90 = uppercase A-Z, 97-122 = lowercase a-z) I suppose. Or indeed, use
String.prototype.isUpper = function(pos){
var chr= this.charAt(pos);
return chr === chr.toLowerCase();
};
KooiInc
2009-06-22 13:36:15
+5
A:
More specifically to what is being asked. Pass in a String and a position to check. Very close to Josh's except that this one will compare a larger string. Would have added as a comment but I don't have that ability yet.
function isUpperCase(myString, pos) {
return (myString.charAt(pos) == myString.charAt(pos).toUpperCase());
}
function isLowerCase(myString, pos) {
return (myString.charAt(pos) == myString.charAt(pos).toLowerCase());
}
maleki
2009-06-22 13:49:02
+1
A:
The answer by josh and maleki will return true on both upper and lower case if the character or the whole string is numeric. making the result a false result. example using josh
var character = '5';
if (character == character.toUpperCase()) {
alert ('upper case true');
}
if (character == character.toLowerCase()){
alert ('lower case true');
}
another way is to test it first if it is numeric, else test it if upper or lower case example
var strings = 'this iS a TeSt 523 Now!';
var i=0;
var ch='';
while (i <= strings.length){
character = strings.charAt(i);
if (!isNaN(character * 1)){
alert('character is numric');
}else{
if (character == character.toUpperCase()) {
alert ('upper case true');
}
if (character == character.toLowerCase()){
alert ('lower case true');
}
}
i++;
}
A:
Regular Expressions anyone. This is how you perfectly do this with RegExp:
var check = /[:lower:]/;
alert(check.test("R")); //False
alert(check.test("r")); //True
alert(check.test("1")); //False
Pablo
2009-11-11 21:42:47